Deformation monitoring at Twin Buttes

When magma moves into a volcanic system, and closer to the surface of the earth, the area surrounding the
volcano may move upward and outward. At Lassen Volcanic Center, this swelling is measured using the Global
Positioning System (GPS).

Continuously recording GPS instruments are the most used type of volcanic deformation-monitoring equipment
in the world. 24 satellites, orbiting the Earth twice each day, transmit their position in orbit to receivers on the
surface of the Earth. The receivers record vertical and horizontal position, and by comparing these
measurements through time, it is possible to determine the amount of movement for a specific location on the
surface of the earth.

There are currently three GPS receivers that make up the continuous deformation monitoring network at Twin
Buttes.